Then What is LAC
By Now One would have got an idea that LAC is actually no line. It is not a line that exists on maps nor does it exists on ground detracted or eliminated by any physical features like a watershed or river or bu pillers.
Here it is but natural for anyone to ask that when the physicality of geography is concerned how does our troops protect it if it does not exist? How do troops dominate and conveyed their control by patrolling? How does MEA communicate and negotiate when it is not a physical reality?
The answer is that there indeed are lines that exist.
First there is a line which has been given to the troops, agencies, and people on the ground to follow, Army, ITBP or other agencies like police forces follow that line to conduct their routine of policing, guarding and defending. However that line is not LAC, It is just a working line. That line is decided at the very highest level based on numerous considerations. It that as an executive order, say for example Indian Armed Force will Patrol up to finger 5 in 33N56 and 76E45 in PengangTso Area.
Second, there is a line or there are many lines that exist based on which the MEA conduct their diplomatic business with China, Those lines are based on past communications, practices, traditions or exchanges. For the purposes of negotiation, there can be many such lines. This line though not conveyed as a line is actually conceptually the actaul LAC. MEA for example conveys
"The PLA came five km inside India up to 31N45 and 76E45 and thereby violated the LAC".
Here MEA has conveyed a point which they consider as LAC. and China by coming to a point has coveted their perception of LAC.
Third. then there are certain points on border which each other consider as border between the two countries - It could be kanchanjunga peak or Bumla or Lipulekh pass etc, They also constitute valid LAC points.